Process for improving the resistance to shrinking and felting of fabrics



Patented Dec. 1, 1953 STATES OFFICE PROCESS FOR- IMPROVING THE RESIST- ANGE T SHRINKING AND 'FEL'IING 0F FABRICS Kern E, Folkcrs, Winchester, Mass, assisnor to Monsanto Chemical Compa corporation of Delaware St. Louis, M9 3 No Drawing. Application January 13, .1950, .Serial No. 1138,5251

L9 C aims.

heating vthe treated Ffabric at .relativelyhigh tem-' peratures in the presence of .a curing cataly t for the condensation product. This process requires high curing temperaturesand relatively long incuring times and has the disadvantages, among others of requiring special equipment and of imparting undesirable physical characteristics to the ,fabrics. These undesirable characteristics include yellowing, tendering, :harsh hand etc. ,It has also been proposed heretofore to treat fabrics with highly acidic aqueoussolutions of melamineformaldehyde condensation products, "which solutions are prepared byrdissolving a partially polymerized or hydrophobic melamine-formaldehyde condensation product in a concentratedaqueous solution of an organic acid, followed byheating of the fabric to insolubil-ize the condensation prodnot. This gprocess has the disadvantage, among others, of requiring th use of 1a treating solution which has insuffioi nt stability for use in ommerci a1 .mill operations.

Both of the labovefdescribed processes have the added disadvantage of requiring the deposition of lirom ,8 to 25% of ithecondensation-product on the weight of ltheifabric, dependin ion the nature of the fabric treated, ior adequate shrinkageand felting control. The ,use of such large tam l l i of condensation product is considered objectionable by the trade partly because of the ,-resulting high cost of the -finished fabric and partly 1-because of the undesirable adlal t and handle limparted to thefabric.

In accordance with ithepresent invention .itis possible to treat fabrics c ntaining wool orothe animal yarns a relatively stable aqueous bath of a potentially eresinens substance which can be ninsolubiliaed at low temperatures an 91D- .plied to the fabric 21-h small concentr ti ns Wi h- ;out yellowing :01 tendering the fabric and with? o i pa n a harsh handle there o, a d at the same time I-impart -exceptional resistance to shrinking vand ifelting,

It is accord n ly one ohiect of the present inyention :to provideian improved process yfOI treatiing ,I-abrics containing wool loraother-animalyarns for improving the resistance of such iiabrios to shrinking and :feltine.

2 A further object of the present inventio s t treat fabrics containing wool or other animal yarns with small amounts of a po nt l y resin one substance which is insolubilized at relatiyely w temperatures an which pr vides a fims fabric which is highl resi ta t o shri king and fe ti g wh e et in ng the. soft hand of th 11. 1- treated Iabric,

Still further objects and advanta es of th P s nt invention wi l ap ear in the follow g description and the apnendedclaims.

The pr e ses of th invention are carr ed ut, in genera by fi st impregnating a .fabr o oontainin-e wool or o h r animal yarns with relatively dilute acidic aqueous colloidal solution of a partially p lym ized m t yl ted methy o melamine o m thyl zetherof :amethylo e amin condens tion product havin .a mo] ratio of comb d ormaldehyde oinelam-ine of at least 2 .8 t 1 or higher. After the fabric has been impresnated with the colloidal solution, forexarnple, by ing t e iabri in a ba h o t e co loidal solution, the fabric is then extracted, .ior exam e by passing it through amanele .or padro h centratioh of the colloidal solution and de ree of extraction being adjusted so to deposit fro 2.5 to 8% by We h f t e conden ation product, hased on the weightof theiabrio. flvhefahr is then dried and the condensation product insolubilizedon th fabr by heating the fabri a relative y low t m eratu es- The "colloidal solutions employe herei may b -prepared a yariety f ways- On suitable method of preparation consists n first :iorm ns an aqueous solution of a wat -soluble methy th r f m t yl l melam ne c ndensatio p od-- not having a PH between H a d l1 d taining at least 3.4 -mols f c m ined v .r-m"-i deh de andiprefe ably at ea t 2 .mo oiicombin methanol iorleaoh moi of melamine i- -th condensation product. ';I,

so ution then ix d wit a water-so uble or anic acid s ected f om the the basis of a :by wei h solution o th co .cl nsa-tio,n product, .or .hy us ng t e. am amoimts of hydroxyacetic .(elycollic) acid ins eadoi aceti acid. o y vnsine hom 1.2 to 3% by we gh o the condensation product, the particular amount of acid used being dependent on the particular species of acid employed. I

Of the organic acids employed to prepare the colloidal solutions acetic acid is the cheapest and the most suitable for this use. It is therefore preferred for use in forming thecolloidal'solutions of the condensation product. When acetic acid is used it is preferred to use from 6.5 to 8% by weight of acetic acid calculated .on the basis of a solution of the condensation product.

4 ferred, however, to use an aging period of 6 to hours.

The formation of the colloidal solution of the condensation product is further evidenced by the fact that the condensation product therein becomes substantive to cotton fibers. This is in contrast to the original solution of the condensation product since the condensation product in such solution is not substantive to cotton fibers prior to acidifying and aging. The substantivity of the colloidal particles to cotton fibers is also strong evidence that they are positively charged since it is generally believed that cotton fibers have a negative charge in the presence of water.

.Theco'lloidal solutions are further characterized r by the fact that the particles of condensation When using hydroxyacetic acid it is preferred to use from '7 to 8.5 of such acid calculated on the basis of a 10% solution of the condensation product. When using formic acid it is preferred to use from 1.4 to 2% of such acid calculated on the basis of a 10% solution of the condensation product.

After the acid has been added to the 6 to 12% aqueous solution of the condensation product,

the resulting solution is aged at least until the particles of condensation product contained therein polymerize sufficiently to attain colloidal size. The formation of the colloidal solution is evidenced in part by a change in the appearance of the original solution. The original solution is water clear but after standing at a temperature,

for example, of 70 to 90 F. for about 4 hours it develops a bluish opalescence or haze and gives the characteristic Tyndall effect of colloidal solutions. At these temperatures a 6 hour aging period is generally suitable for developing colloidal sized particles under mill conditions. The colloidal solutions are generally still suitable for use after aging for '72 to 168 hours.

The viscosity of the solution is one criterion for determining its suitability after prolonged periods of aging. A 10% colloid solution of the condensa-. tion product, after 4 to 6 hours of aging, has a viscosity of about 3 to 5 centipoises. The viscosity does not change to any appreciable extent during aging until a relatively short period of time prior to the conversion of the colloidal solution to a thick jelly or gel. Then the viscosity rises relatively rapidly and gelation generally takes place within a period of 1 to 5 hours. Generally the colloidal solution is usable until its viscosity rises above 15 centipoises. After that the colloidal solution may become unfit for use during the treatment of the fabric.

The aging temperature and exposure of the solution to air have a marked influence on the rate of formation of the colloidal solution and the rate at which such solution finally converts to a gel. At temperatures below 70 F., that is, between about 40 F. and 70 F., the colloidal solution forms at a relatively slow rate and the original solution may require more than a 6 hour aging period before it is converted to a colloidal solution. At temperatures above 90 F., that is,

temperatures of 100 to 200 F. the colloidal solution forms at a relatively rapid rate and the original solution may be satisfactorily converted to a colloidal solution within a 3 hour aging period.

Exposure of the colloidal solution to air decreases product therein are not substantive to wool or other keratinous fibers, that is to say, such particles do not migrate from the colloidal solution to the wool fibers.

The condensation product in the colloidal solution is characterized by the fact that it contains at least 2.8 mols of combined formaldehyde for each mol of melamine therein. The ratio of combined formaldehyde to melamine is higher than 2.8 to 1 in those instances where the original methyl ether of methylol melamine condensation product contains from 3.5 to 6 mols of combined formaldehyde and more than 2.5 mols of combined methanol for each mol of melamine. Methyl ethers containing 6 mols of combined formaldehyde and from 5 to 6 mols of combined methanol may also be used to prepare the colloidal solutions employed herein. However, such products are quite expensive to prepare. Moreover, they do not show any advantage and are not as stable in colloidal form, in most instances, as the lower methylated products described above. Best results are obtained by using colloidal solutions which are prepared from methyl ethers of methylol melamine condensation products which these products are, accordingly, preferred.

The methyl ethers of methylol melamines employed in this invention are commercially available products and may be prepared in various ways. A suitable method for their preparation consists in first reacting melamine and formaldehyde, as formalin, in mol ratios of about 113.5 to about 1:8 in an alkaline reacting solution at a temperature between about 60 and C. until the melamine is substantially dissolved. Methanol is then added to this solution for the purpose of forming the methyl ether. In general, from about 10 to 30 mols of methanol are employed for each mol of melamine used. The solution is then acidified to a pH between about 2 and 5 with a strong mineral acid such as phosphoric acid, hydrochloric acid and the like. This mixture is heated to a temperature between about '30 and 60 C. until a homogeneous solution is obneutralization of the excess mineral acid with the fixed alkali may be removed. if desired. by

filtering, centrifuging or the like. The; solution and percentages being by weight unless otherwise specified.-

Emample I A. Preparation of a. water solution of a watersoluble methyl ether of'methylol melamine.--One hundred and twenty-seven parts approximately 1 mol) of melamine were mixed with 365' parts of a 37% aqueous solution of formaldehyde (4.5 mols. HCHO). The resulting mixture was adjustedto a pH of 8.6 (glass electrode) with NaOI-I and then heated at a temperature of 70 C. until the melamine was substantially dissolved. After a further reaction of about 5 minutes, 640 parts mols) of methanol were a'dded to the solution and" the pI-I was adjusted to 4.0 (glass electrode) with phosphoric acid. The reaction was then continued for an additional 15 minutes at a temperature of approximately 40 C. The pH of the solution was then adjusted to 10 .5 (glass electrode) with NaOH. The resulting solution was then concentrated by subjecting it to a vacmm of 10 millimeters of mercury at a temperature of C. until it contained 60% Condensation product. The solution was then cooled rapidly to 20 C. The resulting solution was infinitely dilutable with water. The condensation product in the solution was analyzed and was found to contain 3.5 mols of combined formaldehyd'e and 2.2 mols of combined methanol for each mol of melamine used.

B. Preparation of acidic aqueous colloidal solution of methyl ether of methylol melamine.-

One hundred and forty parts of' the 60% solution, as prepared above, were stirred together with 593 parts of water and 109' parts of 56% acetic acid. The resulting solution contained about 10% of the methyl ether of methylol' melamine condensation product and about 7.2% of acetic acid and hada pH of 3.9. The solution was. allowed to age for Ghours at 85" F. During this aging the particles of the condensation product became colloidal in'size as evidenced by the bluish haziness of the solution and by the fact that it gave the Tyndall. effect which is characteristic of' colloidal solutions. The colloidal particles of partially polymerized condensation product were substantive to cotton fibers but were not. substantive to wool fibers or other animal fibers. This colloidal solution had v a pH of 3.7. The condensation product was analyzed and contained 2.9. mols of combined formaldehyde for each mol of melamine.

C. Treatment of all wool fabric-Three" hun-' red. parts of the colloidal solution, prepared as described inparagraph B above, were diluted with 200 parts of water; The resulting colloidal solution. contained6% condensation product. A

' piece of essentially neutral and substantially oilfreeallwool plaid fabric waswetted out in this colloidal'solution. and then extracted by passing it between pad rolls set at a pressure of 40 pounds per linear inch. This gave a pickup of ofsolution on the weight of the fabric. About 4% of the condensation product on the weight of the: fabric was deposited. The fabric was dried for 10 minutes at'200'F. and then heated for an additional 10 minutes at 250 F. to insolubilize. the

condensation product. The fabric was next filling dimensions and was then tion product and'1.6% of 5.5. 7 hours at F. for a period of 6' hours. After this '0 rinsed'for' 5 mmutes in water at: a temperature of F., scoured for 10 minutes inra 0:1 water solution of dodecyl benzene so'diumsulfonate. at a temperature of110 F. and finally rinsed in water at 110 F. The fabric exhibited no yellowing or tendering and'had an exceptionally soft hand.

D. Shrinkage and felting results.-The treated fabric, as prepared according. to paragraph C above, was first; measured along the warp and washed for 60 minutes in water adjusted to a pH between 5 and 7 with a buffer and at a temperature of F. This. wash is equivalent to 10 standard AATGC (American. Association of Textile Chemists and Colorists) wool washes. The fabric was again measured along the warp and filling dimensions.

A piece of neutral oil-free all wool plaid fabric from: the same roll was processed in exactly the same manner except that it was not treated with the colloid solution of the condensation product.

The following table shows the percent total shrinkage and the percent felting shrinkage of the treated and untreated fabric along the warp and filling dimensions.

A. Preparation of'acz'dic aqueous colloidal solution of methyl ether of methylol melamine.-Two hundred and eighty parts of the 60% solution prepared in accordance with paragraph A of Example I, were stirred together with 1376 parts of water and 28 parts of 100% formic acid. The resulting solution contained about 10% of the methyl ether of methylol melamine condensaformic acid and had a pH This solution wasailowe'd to age for 6 period of aging the solution was converted to a colloidal solution having a bluish hazy appearance and a viscosity of 4 centipoises. The colloidal particles of partially polymerized condensation product were substantive to cotton fibers, but were not substantive to wool fibers. This colloidal solutionhad a pH of 5.3. Analysis showed that the condensation product therein contained 2.95 mols of combined formaldehyde for each mol of melamine.

B. Treatment of all wool ,fabric.Six hundred parts of the colloidal solution, prepared as. described immediately above, were diluted with 400 parts of water. The resulting solution contained 6% condensation product. A piece of essentially neutral and substantially oil-free all wool plaid fabric was wetted out in this colloidal solution and then extracted by passing it between pad rolls adjusted to give a pick-up of 86% of solution on the weight of the fabric. About 5.1 %v of the condensation product was thereby deposited on the fabric. The'fabric was dried for 10' minutes at F. and then heated for an additional 10 minutes at 250 F. to insolubilize the condensation product. The fabric was. next rinsed. for 5 minutes in water at 1"10'F.", scoured-for 10minutes in an 0.1% water solution of dodecyl benzene sodium sulfonate at a temperature of 110 F. and finally rinsed in water at 110 F. The resulting fabric exhibited no signs of yellowing or tendering, and had an exceptionally soft touch or hand.

C. Shrinkage and felting results.The treated fabric, as prepared immediately above, was first measured along the warp and filling and was then washed for 60 minutes in water adjusted between a pH of 5 and '7 with a buffer and at a temperature of 140 F. The fabric was again measured along the warp and filling dimensions.

A piece of neutral, oil-free, all wool plaid fabric from the same roll was processed in exactly the same manner except that it was not treated with the colloidal solution of the condensation .product.

The following table shows the percent total shrinkage and the percent felting shrinkage of the treated and untreated fabric along the warp and filling dimensions.

Percent Total Percent Felting Shrinkage Shrinkage Warp Filling Warp Filling Treated Fabric 7. 1 l. 3 5. 2 0. 7 Untreated Fabric 22. 16.0 18.5 14.1

Example HI A. Preparation of acidic aqueous colloidal solution of methyl ether of methylol melamine- Two hundred and eighty parts of the 60% solution prepared in accordance with paragraph A of Example I were stirred together with 122 parts of 100% hydroxy acetic acid and 1282 parts of water. The resulting solution contained about 10% of the methyl ether of methylol melamine condensation product and about 7.2% of hydroxy acetic acid. The solution was allowed to age for 30 hours at a temperature of 80 F. At the end of the aging period the solution had a bluish opalescent appearance and the particles of partially polymerized condensation product were substantive to cotton fibers, but not to wool fibers. The solution was analyzed and it was found that the condensation product therein comprised 2.9 mols of combined formaldehyde per mol of melamine.

B. Treatment of all wool fabric.-Three hundred and sixty parts of the colloidal solution, prepared as described immediately above, were diluted with 240 parts of water. The resulting solution contained 6% condensation product. A piece of essentially neutral and substantially oil-free all wool plaid fabric and wetted out in this colloidal solution and then extracted by passing it between pad rolls adjusted to give a pick-up of 88% of solution on the weight of the fabric. About 5.3% of the condensation product was thereby deposited on the fabric. The fabric was dried for 10 minutes at 180 F. and then heated for an additional period of 10 minutes at 250 F. to insolubilize the condensation product. This was followed by rinsing the fabric for minutes in water at 110 F., scouring the fabric for minutes in a 0.1% water solution of dodecyl benzene sodium sulfonate at a temperature of 110 F. and finally rinsing the fabric in water at 110 F. The treated fabric exhibited no signs of yellowing or tendering and possessed an exceptionally soft hand.

The following table illustrates the percent shrinkage and percent felting shrinkage of the treated fabric and a control fabric after 1 wash such as that described in paragraph C of Example Il.

A. Preparation of methyl ether of methylol melamine.-One hundred and twenty-seven parts (approximately 1 mol) of melamine were mixed with 485 parts parts of a 37% aqueous solution of formaldehyde (6 mols HCHO). The resulting mixture was adjusted to a pH of 8.5 (glass electrode) with NaOH and then heated at a temperature of 70 C. until the melamine was substantially dissolved. After a further reaction of about 5 minutes, 640 parts (20 mols) of methanol were added to the solution and the pH was adjusted to 4.0 (glass electrode) with hydrochloric acid. The reaction was then continued for an additional 20 minutes at a temperature of approximately 40 C. The pH of the solution was then adjusted to 10.5 (glass electrode) with NaOH. The resulting solution was then concentrated by subjecting it to a vacuum of 5 millimeters of mercury at a temperature of 60 C. until it contained 50% condensation product. The solution was then cooled rapidly to 25 C. It was infinitely dilutable with water. The condensation product in the solution was analyzed and was found to contain 5.3 mols of combined formaldehyde and 2.9 mols of combined methanol for each mol of melamine used.

B. Preparation of acidic aqueous colloidal solution of methyl ether of methylol melamine- One hundred and sixty-eight parts of the 50% solution, as prepared immediately above, were stirred with 565 parts of water and 109 parts of acetic acid (56%). The resulting solution contained about 10% of the methyl ether of methylol melamine condensation product and about 7.3% of acetic acid. The solution was allowed to age for 6 hours at F. during which time it developed a bluish opalescent appearance and the particles of partially polymerized condensation product became substantive to cotton fibers, but

0. Treatment of all wool flanneL- I'hree hundred and sixty parts of the colloidal solution as prepared immediately above, were mixed with 240 parts of water to form a colloidal solution containing 6% of the condensation product. A piece of essentially neutral and substantially oilfree all wool 8 ounce flannel fabric was wetted out in this colloidal solution and then extracted by passing it through pad rolls adjusted to give a pick-up of 10% of solution on the fabric weight. Approximately 4% of the condensation product, on the weight of the fabric, was thereby deposited. The fabric was next dried at 190 F. for 10 minutes and heated for an additional 12 minutes at 250 F. to insolubilize the condensation product. After this'the fabric was rinsed for 10 minutes in water at 110 F., scoured for 10 minutes in a 0.2% water solution of dodecyl benzene sodium sulfonate at a temperature of 110 Hand finally rinsed in water at 110 F. The

ass-eels of wool or other animal yarns. The fabric to be treated is preferably dyedpr-ior to the treatment with the colloidal solution.

The amount of colloidal solution pickedup by the "fabric after wetting out orimpregnating by dipping may be varied-tolsome extent depending upon the extracting equipment used and the amount of condensation product which-it is desired to apply to the fabric. The pick-up of solution preferably should notexceed about 110% by weight based on the fabric as dusting of the cured resin becomes noticeable and oftentimes undesirable at higher pick-ups. It was pointed out earlier in the description of this invention that 3.5 to 8% by weight of the condensation product is applied to the fabric. This amount is readily applied to the fabric by using colloidal solutions containing from 3.5 to 12% by weight of the condensation product and then extracting the fabric until the desired weight of condensation product is deposited thereon.

The drying and curing conditions set forth in the examples and elsewhere in this description may be varied considerably. For example, it is possible to dry the fabrics at other temperatures, for instance, at temperatures of 120 to 200 F. and it is also possible to cure the fabrics, that is, insolubilize the condensation product at temperatures of 200 to 325 F. It is also possible to dry the fabric and insolubilize the condensation product in one operation, for example, by heating the extracted fabric after the treatment with the colloidal solution to a temperature of 200 to 325 F. A preliminary drying prior to insolubilization of the condensation product is preferable, however, since this reduces the tendency of the condensation product to migrate to the fabric surface, thereby imparting a somewhat harsh handle.

The duration of drying or curing may also be varied considerably. In general, the fabric is dried for a period of to minutes. The time required for curing depends primarily on the temperature used, lower temperatures requiring longer curing periods. In general, the condensation product is insolubilized or cured satisfactorily within a period of from 5 to 15 minutes at temperatures of from 325 to 200 F.

Various modifications and changes may be made in the processes and compositions of this invention as will be apparent to those skilled in the art to which it appertains without departing from the spirit and intent of the present invention. Accordingly, it is intended that this invention be limited only by the scope of the appended claims.

What is claimed is:

1. A process of improving the resistance to shrinking and felting of fabrics comprising animal yarns which comprises wetting out the fabric in an acidic aqueous colloidal solution of (1) a 10 paaauy polymerized positively charged :methyl *ether of methylolmelamine condensation product containing from J258xto 6 mols of combined .formaldehydeper :mol of melamine and (2) .a water-soluble organic acid selected from "the group consisting 'of acetic acid, hydroxyacetic acid "and formic acid; extracting the fabric :to deposit from 3.5 to 8% by weight, based onthe fabric, of said condensation product; and heat- ,ing said fabric at temperatures between 200 and 325F. to insolubilize said condensation product.

, f 2. A rocess of improving the resistance to shrinking and felting of fabrics 'comprisinganimal fibers which comprises wetting out the fabric in an acidic aqueous colloidal solution of (1) from 3.5 to 12% by weight of a partially polymerized positively charged methyl ether of methylol melamine condensation product conlta'ining'from 2.8 ;to 6 mols of combined formal- 'dehyde"per'ijmolcof'melamme and (2) from 1.2 to'8;5% by weight, calculated on the basisjof a 10 by weight solution .of the condensation-prod- :uc'tgof a water-solubleorganic acid selected from the group consisting :of acetic acid, hydroxy "acetic acid and formic acid; extracting thefabric to deposit from 3.5 to 8% by weight, based on the fabric, {of said condensation product; and

heating said fabric at temperatures between. 200 and 325 F. to insolubilize said condensation product.

3. A process of improving the resistance to shrinking and felting of fabrics comprising at least 50% by weight of wool yarns which comprises wetting out the fabric in an acidic aqueous colloidal solution of (1) from 3.5 to 12% by weight of a partially polymerized positively charged methyl ether of methylol melamine condensation product containing from 2.8 to 6 mols of combined formaldehyde per mol of melamine and (2) from 6.5 to 8% by weight, calculated on a 10% by weight solution of said condensation product, of acetic acid, said solution being at a temperature of about '70 to F.; extracting the fabric to deposit from 3.5 to 8% by weight, based on the fabric, of the condensation product; and then heating the fabric at temperatures of 200 to 325 F. to insolubilize said condensation product.

4. A process of improving the resistance to shrinking and felting of fabrics comprising at least 50% by weight of wool yarns which comprises wetting out the fabric in an acidic aqueous colloidal solution of (1) from 3.5 to 12% by weight of a partially polymerized, positively charged methyl ether of methylol melamine condensation product containing from 2.8 to 6 mols of combined formaldehyde per mol of melamine and (2) from 7 to 8.5% by weight, calculated on a 10% by weight solution of the condensation product, of hydroxy acetic acid, said solution being at a temperature of 70 to 90 F.; extracting said fabric to deposit from 3.5 to 8% by Weight, based on the fabric, of the condensation product; and heating said fabric at temperatures between 200 and 325 F. to insolubilize said condensation .product.

5. A process of improving the resistance to shrinking and felting of fabrics comprising at least 50% by weight of wool yarns which comprises wetting out the fabric in an acidic aqueous colloidal solution of (1) from 3.5 to 12% by weight of a partially polymerized, positively charged methyl ether of methylol melamine condensation product containing from 2.8 to 6 mols of combined formaldehyde per mol of melamine 11 and (2) from 1.4 to'2% by weight, calculated on a 10% by weight solution of the condensation product, of formic acid, said solution being at a temperature of '70 to 90 F.; extracting said fabric to deposit from 3.5 to 8% by weight, based on the fabric, of the condensation product; and heating said fabric at temperatures of 200 to 325 F. to insolubilize said condensation product.

6. A process substantially according to claim 2, but further characterized in that the organic acid used is acetic acid and it is used in an amount suflicient to provide a solution containing from 6 to 8.5% by weight of said acid calculated on the basis of a 10% by weight solution of the condensation product. I

'7. A process susbtantially according to claim 2, but further characterized in that the organic acid used is hydroxyacetic acid and it is used in an amount sufficient to provide a solution containing from 6 to 8.5% of said acid calculated on the basis of a 10% by weight solution of the condensation product.

8. A process substantially according to claim 2, but further characterized in that the organic acid used is formic acid and it is used in an amount sufficient to provide a solution containing from 1.2 to 3% by weight of said acid cal culated on the basis of a 10% by weight solution of the condensation product.

9. A process of improving the resistance to shrinking and felting of fabrics comprising animal yarns which comprises wetting out the fabric in an acidic aqueous colloidal solution of (1) a partially polymerized positively charged methyl ether of methylol melamine condensation product containing from 2.8 to 6 mols of combined formaldehyde and from 2 to 6 mols of combined methanol per mol of melamine and (2) a watersoluble organic acid selected from the group consisting of acetic acid, hydroxyacetic acid and formic acid; extracting the fabric to deposit from 3.5 to 8% by weight, based on the fabric, of said condensation product; and heating said fabric at temperatures between 200 and 325 F. to insolubilize said condensation product.

KERN E. FOLKERS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,191,362 Widmer et a1 Feb. 20, 1940 2,345,543 Wohnsiedler et a1. Mar. 28, 1944 2,395,791 Pfeffer et a1 Feb. 26, 1946 2,417,014 Pollard Mar. 4, 1947 2,429,073 Rickus et a1. Oct. 14, 1947 2,485,080 Wohnsiedler et a1. Oct. 18, 1949 

1. A PROCESS OF IMPROVING THE RESISTANCE TO SHRINKING AND FELTING OF FABRICS COMPRISING ANIMAL YARNS WHICH COMPRISES WETTING OUT THE FABRIC IN AN ACIDIC AQUEOUS COLLOIDAL SOLUTION OF (1) A PARTIALLY POLYMERIZED POSITIVELY CHARGED METHYL ETHER OF METHYLOL MELAMINE CONDENSATION PRODUCT CONTAINING FROM 2.8 TO 6 MOLS OF COMBINED FORMALDEHYDE PER MOL OF MELAMINE AND (2) A WATER-SOLUBLE ORGANIC ACID SELECTED FROM THE GROUP CONSISTING OF ACETIC ACID, HYDROCYACETIC ACID AND FORMIC ACID: EXTRACTING THE FABRIC TO DEPOSIT FROM 3.5 TO 8% BY WEIGHT, BASED ON THE FABRIC, OF SAID CONDENSATION PRODUCT; AND HEATING SAID FABRIC AT TEMPERATURES BETWEEN 200 AND 325* F. TO INSOLUBILIZE SAID CONDENSATION PRODUCT. 